gulp-rev expects files to be copied to buildDir

Fixes an issue when multiple src files are passed to config.version
gulp-rev process must run after deleting buildDir
Merge branch 'james2037-patch-1'
Minify is disabled for dev mode.

Instead, use the —production flag from the command line.

gulp —production
Unused var
Move env check into config file
Merge two lines
Use Sass as default suggestion
Merge remote-tracking branch 'upstream/master'

Conflicts:
	package.json
Merged upstream, and fixed conflicts.